Generally speaking, for taking up yarns extruded from a spinning machine a yarn winder is used. The yarn winder comprises a spindle rotatably carried on a machine frame for carrying bobbins and a traverse-motion mechanism mounted on the machine frame above the spindle while being movable upward and downward or a turret type yarn winder in which a plurality of spindles for carrying bobbins are rotatably carried on a turret member which, in turn, is rotatably mounted on a machine frame.
A traverse-motion mechanism used for a high-speed winder comprises a plurality of traversing units, each consisting of a pair of rotors carried on a frame at a distance from each other, a plurality of blades secured onto the respective rotor, and a yarn guide fixed to the frame so as to be located in the path of a yarn-guiding edge of the blade. The traversing units are arranged at a predetermined pitch in the lengthwise direction of the bobbin-carrying spindle, while a touch roller is rotatably carried on the frame close to the blade of the respective traverse unit at a position downstream thereof.
The blades are positioned around the rotor at an angular pitch of 180.degree. and 120.degree. when the number of blades is two and three, respectively. A pair of rotors, each provided with the same number of blades, are secured on the frame at a distance therebetween and rotatable in the reverse direction to each other.
A traverse-motion mechanism having a plurality of such traversing units is disclosed, for example, in Japanese Examined Patent Publication Nos. 3-72544 (corresponding to the U.S. Pat. No. 4,505,436) and 4-27151 (corresponding to the U.S. Pat. No. 4,505,437).
Recently, spindles tend to be lengthened to increase the number of bobbins (four through eight) to be carried thereon for the purpose of increasing yarn-winding capacity.
The lengthening of spindle, however, causes the increase of a yarn bending angle at a yarn-separating fulcrum directly beneath a godet roller on the upstream side toward a yarn-traversing fulcrum positioned at the respective end of the spindle, which, in turn, results in the deterioration of yarn quality due to the increase of running resistance at the fulcrum. In addition, since the yarn is taken up by a higher winding tension, a yarn package thus obtained is difficult to unwind.
According to the abovesaid limitation of the yarn bending angle at the yarn-separating fulcrum toward the yarn-traversing fulcrum, it is impossible to shorten the distance between the traversing unit and the yarn-traversing fulcrum and that between the yarn-traversing fulcrum and the yarn-separating fulcrum disposed upstream thereof. This increases a height of the yarn-separating fulcrum disposed upstream of the yarn-traversing fulcrum and that of the godet roller disposed at further upstream position, whereby the threading operation becomes difficult. In addition, there is a problem in that a total height of the machine increases, whereby it can be installed only in a building having a high ceiling.
According to the abovesaid traverse-motion mechanism, since the blades mounted on the respective rotors have the same diameter (D) and the rotors are positioned at a distance in the bobbin axial direction. When the first and second rotors are driven from the same side, as shown in FIG. 14, a pitch L between the adjacent traversing units cannot exceed a sum of an outer diameter D of the blades of the rotor and a diameter d of a rotor shaft, i.e., (D+d)/2. For example, if it is assumed that a traversing stroke W is 250 mm, the outer diameter D of blades is 540 mm and the diameter d of a rotor shaft is 30 mm, the pitch L of the traversing units is determined by the following formula: ##EQU1##
On the other hand, a gap of about 25 mm is sufficient between the adjacent full packages for manipulating them.
This means that a length of 10 mm obtained by subtracting a sum of the traversing stroke W (250 mm) and the indispensable gap (25 mm) from the pitch L (285 mm) is excessive. Due to this excessive length, longer bobbins and a long spindle must be used, whereby an increase in yarn winding speed is restricted.
In addition, since the distance between the rotors in the respective traversing unit is very short, it is hardly possible to directly transmit the rotation of one rotor to the other. Accordingly the each of them must be adapted to intermesh with a common intermediate gear through a gear fixed with the respective rotor so that one rotor is rotatable when the other rotor is driven by a common driving mechanism.
There are problems, inherent to the provision of an intermediate gear or the like, of the structural complexity and the need of time for the production of parts, assembly and maintenance thereof.
A yarn package taken up via the abovesaid traverse-motion mechanism has the drawback of an increase in package selvage and ribbon wind because the turning points of the traversing stroke and a running trace of yarn are constant from the initiation to the completion of the package formation.
Accordingly, to minimize the increase in package selvage and the ribbon wind, a method is proposed for providing a plurality of turning points and running traces of yarn, by using a rotor with blade, each having a yarn-guiding edge different from the other (which is called a "selvage-rise flattening method").
Such a traverse-motion mechanism for providing a plurality of turning points is described, for example, in Japanese Examined Patent Publication (Kokoku) No. 49-2394.
The method adopting such the blades, each having a different shape from the other, has drawbacks in that the number of turning points is at most equal to that of blades, a stepped selvage is liable to occur when the number of turning points is as few as two or three, and the traverse-motion mechanism becomes too large to put into practice when as many as six through eight blades are used to minimize the rise of selvage.
Accordingly, the first problem to be solved by the present invention is the difficulty of the threading operation due to the increase of distance of yarn-separating fulcrum or godet roller from a yarn-traversing fulcrum disposed downstream thereof.
A second problem is that the winder becomes too large to be installed in a building except for one having a particularly high ceiling.
A third problem is that, since the pitch of traversing units cannot be shortened, unfavorably longer bobbins and spindles must be used.
A fourth problem is that, since the distance between axes of the adjacent rotors is very small in a traverse-motion mechanism having a pair of rotors, each provided with the same number of blades, such as two or three, it is necessary to provide a part such as an intermediate gear for driving one rotor by the other rotor, which increases the complexity of the structure and results in an increase in time for the production of parts, and assembly and maintenance thereof.
A fifth problem is that the number of turn points is at most three even if each of three blends has a yarn-guiding edge with a different shape from the other, whereby it is impossible to minimize the rise of package selvage and the ribbon wind to an extent not influencing the package quality.
A sixth problem is that a turning point cannot be changed unless a blade is replaced with a new one.